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E. H. JOHNSTON.

INTBRLOGKING SWITCH AND SIGNAL MECHANISM.

No. 253,391. Patented Feb. 7,1882.

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v INTERLOCKING $WITGE AND SIGNAL MECHANISM No. 253,391. Patented Feb. 7,1882.

UNITED STATES PATENT OFFICE.

EDWARD H. JOHNSTON, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO THE WHARTON RAILROAD SVVITUH COMPANY, OF SAME PLACE.

INTERLOCKING SWITCH AND SIGNAL MECHANISM.

SPECIFICATION forming part of Letters Patent No. 253,391, dated February '7, 1882. Application filed August 29, 1881. (N0 model.)

To all whom it may concern:

Be it known that I, EDWARD H. JOHNSTON, a citizen of the United States, residing in Philadelphia, Pennsylvania, have invented an Improvement in Interlocking Switch and Signal Mechanism for Railways, of which the following is a specification.

My invention consists of mechanism, fully described hereinafter, for operating switches and danger signals on railways; and the object of my invention is to prevent the opening of the switch and the consequent interruption of the continuity of the main track without first giving the danger-signal, and to prevent the giving of a safety-signal without first closing the switch and thereby restoring the main track to a condition for the travel of trains thereon.

In the accompanying drawings, Figure 1, Sheet 1, is a side View of my improved safety device for operating switches and signals; Fig. 2, an end View of Fig. 1; Fig. 3, an inverted perspective view of the pivoted safetyplate; Fig. 4, Sheet 2, a plan view of Fig. 1, partly in section; and Figs. 5, 6, 7, and 8, views showing the different positions of the safetyplate and switch and signal levers under the circumstances explained hereinafter.

To a frame, A, consisting in the presentinstan'ce of two castings, a a, suitably connected together and secured to the track, are pivoted the two levers B B, the former being connected to the danger-signal and the latter to the switch. Each of these levers is provided with a spring-bolt, b, adapted to notches in the frame, so that the lever may be locked in either of the two positions to which it has to be moved. It will not be necessary to describe this locking device, as it is similar to that used on the starting, stopping, and reversing lever of a locomotiveengine. It is not essential to my invention, moreover, to adhere to this locking device shown in the drawings.

A safety-plate, D, is pivoted by a pin or bolt, d, to thetop of the frame, and has on the under side a projection, e, which, coming in contact with the frame, serves to limit the movement of the plate but other appliances for this purpose will readily suggest themselves.

The character of this plate and its relation to the switch and signal levers for the'purpose of effecting the desired object can be best explained by reference to the views Figs. 5, 6, 7, and 8. In Fig. 5 the switch-lever B fits in a notch,f, in the safety-plate, on one edge of the same, and the signal lever B being in contact, or nearly so, with the opposite edge of the plate, the latter cannot turn on its pivot, and the switch-lever will consequently be locked.

This is the condition of the levers and safetyplate when the switch is closed and the continuity of the main line uninterrupted.

Should it be necessaryto give the signal of danger due to other causes than an open switch, the signal-lever can be operated without disturbing the switch-lever; but in order to-release the latter the signal-lever must be moved to the position Fig. 6, in doing which it will so act on the inelined'edge h of the safetyplate as to turn the latter on its pivot, as in Fig. 6, and permit the switch-lever to be moved to the position Fig. 7, in doing which the said lever, bearing against the inclined edge 2' of the plate, will turn the latter to the position Fig. 7, where it will be observed that the signal-lever is locked in the notch m of the plate, which cannot be turned, owing to the switch lever. This is the condition of the levers and safetyplate when a switch has been turned to a siding and the main line is not in a condition to be traversed by trains, this being indicated by the danger-signal, which cannot be disturbed as long as the switch is thus open. On moving the switch-lever B, however, in the direction of the arrow, Fig. 7, so as to close the switch, the said lever, bearing against the inclined edge a of the safety-plate, will turn the latter, as shown in Fig. 8, thereby releasing the signal-lever, which can be returned to the position Fig. 5, in doing which the signal-lever, o

acting against the inclined edge 19 ot the plate, will turn the latter, and the switch-lever will be locked as before, the signal indicating that the main track is clear for the travel of trains.

It will be seen, without further description, 5

that the continuity of the main track cannot be interrupted by opening the switch without first giving the danger-signal, and that a safety-signal cannot be given without first closing the switch and restoring the track to a, condition for the travel of trains.

I claim as my invention- The combination of the switch-lever B and signal-lever B with the pivoted safety-plate 1), constructed to directly act on and to be 

